Optical systems in general and endoscopes in particular may include a scanning system so that a two-dimensional image can be constructed of a sample. In some existing systems, this scanning system provides a raster scan comprising a fast scan (usually described as the x-scan) and a slow scan (usually described as the y-scan).
One existing system is disclosed in WO 99/04301. A scanner is mounted in an optical head casing and light is admitted to the optical head casing by means of an optical fibre mounted on the scanner. In a particular embodiment, the scanner comprises a tuning fork to which the optical fibre is attached. The tuning fork is vibrated, which causes the optical fibre to vibrate thereby providing the fast x-scan. The slow y-scan is provided by moving the tuning fork in a direction perpendicular to the fast x-scan vibration, such as by rotating the tuning fork about its longitudinal axis.
Another existing system, disclosed in U.S. Pat. No. 6,294,775, attempts to integrate the provision of the fast and slow scans, by outputting a beam of light from a resident optical fibre in a spiral or a radial scan path.
However, it is always desirable that still smaller scanning systems be developed, particularly for endoscopic applications. Existing systems each have a lower limit to their practical size, owing to the complexity of their construction, the mechanical properties of their materials or the arrangement of their component. In addition, some existing systems are undesirably complex and therefore are more vulnerable to failure or deterioration of performance.